The Holcombe Department of Electrical and Computer Engineering

Pingshan Wang receives grant to develop EPR spectrometers

Pingshan WangECE professor Pingshan Wang has received a three-year, $384,000 grant from the NSF for his project, “CMI Instrument Development: High-Sensitivity, Single-Pass Electron Paramagnetic Resonance Spectrometers” to develop ultra‐sensitive, single‐pass electron paramagnetic resonance (EPR) spectrometers for the study of paramagnetic samples in liquid.

EPR spectrometers are essential and powerful analytical tools for chemistry studies. They measure the electromagnetic energy required to reorient the magnetic moments of unpaired electrons in a magnetic field. The obtained EPR spectrum parameters reveal the molecular structures of the paramagnetic species as well as the dynamic interactions between a paramagnetic species and its microenvironment. Furthermore, EPR spectra exhibit great specificity since most stable molecules do not have un-paired electrons, except radicals and spin-labels. Radicals are important in various chemical processes while spin-labels are well-developed and can be site-directed. Current EPR spectrometers, however, have inadequate sensitivities and time-resolutions
for many chemistry studies.

Dr. Wang's research group proposes to develop novel, single-pass EPR sensors which exploit interference processes within the devices to isolate microwave probing signals from small EPR signals at the output port. The project involves the development of a new methodology, onchip microwave interference, to boost EPR spectrometer sensitivity and time-resolution. Resonators and their limitations, i.e. limited quality factors and the trade‐offs between sensitivity and time-resolution, are avoided. Compared with current EPR spectrometer techniques, the proposed EPR spectrometers have orders of magnitude better sensitivity and time-resolution, as liquid solutions do not deteriorate the performance of our EPR spectrometers. The significantly boosted sensitivity and time‐resolution of the developed EPR spectrometers are expected to enable new chemistry research efforts where these instrument parameters are critical and attract a wide variety of applications in different areas, such as biology, disease and medicine.